This application relates to the art of valves and, more particularly, to valves having means for indicating various operating conditions thereof, and to diaphragm valves of the type having a diaphragm clamped between body and bonnet members. Although the invention will be described with particular reference to diaphragm valves and rotatably operable valve members, it will be appreciated that the invention has broader applications, and that certain individual features thereof may be used with other types of valves and/or in other environments.
Diaphragm valves of known types include a circular diaphragm clamped in a circumferential area between body and bonnet members. The diaphragm fails after a certain number of cycles and may also fail due to the manner in which it is clamped. It has been considered desirable to develop a diaphragm valve which included a diaphragm of increased strength capable of withstanding a greater number of cycles before failure. Such a valve would include means for clamping the diaphragm in a manner insuring good diaphragm sealing while minimizing stress failures.
Valves commonly include indicating means for indicating various flow positions of the valve member. In many applications where metal seal packless valves are used, indication of flow position is critical from a safety standpoint. In previous arrangements, indication of flow position was designated by a simple marking or required the operator to recognize handle orientation relative to the valve body. In the latter case, some types of mountings prohibit this type of recognition.
In previous arrangements, the rotatable operating member is restricted from being moved beyond the set, off position of the valve. If overtravel beyond the off position without adjustment of the valve is not possible, two problems will result after seal wear has occurred. First, the valve cannot be shut off, and second, the handle could be broken by an operator attempting to forcedly close the valve.
When there is no stop means for stopping the operating member in its off position, the operating member may inherently overtravel beyond the off position due to seal wear. Only a highly skilled person would be aware that at some point such overtravel would signify that replacement of the seal was necessary, and there was no associated means for indicating the point at which such seal replacement was necessary. Therefore, it would be desirable to have an alarming indicating means for clearly indicating to an operator that a seal is worn beyond its normal, useful life and that replacement is necessary.
The subject invention meets the foregoing needs and others, and provides a new and improved valve construction.